The present invention relates to article transport vehicles.
Conventional article transport vehicles perform a transfer of articles using travel control means that actuates a drive motor to rotatively drive a pair of front and rear travel wheels in order to move a vehicle body along a travel rail, for example, up to a target article transferring location.
In one such conventional article transport vehicle, the front and rear travel wheels each are provided with a single drive motor, and the vehicle body is moved by rotatively driving the front wheel on the front side and the rear wheel on the rear side of the vehicle body (see JP 2001-240213A, for example).
Compared to article transport vehicles in which only one of the front and rear travel wheels is rotatively driven by a drive motor, the article transport vehicle disclosed by the above patent document attains a larger drive force because the front and rear travel wheels are both rotatively driven by a drive motor, and thus the article transport vehicle can be moved faster, reducing the time necessary for transporting articles.
When an article transport vehicle has a plurality of drive motors, in practice it is difficult for those drive motors to rotate the corresponding wheels in exactly the same manner, and thus it is difficult to improve travel efficiency by increasing the article transport vehicle velocity, for example. That is, communication delays when specifying the target travel velocity, for example, or manufacturing errors between drive motors, for example, prevent the same operation from being obtained even if the plurality of drive motors are controlled in the same manner, and this causes differences in operation between the drive motors and leads to the plurality of drive motors interfering with one another.
Accordingly, in article transport vehicles having a plurality of drive motors, there is a need for a design that would solve or at least alleviate this problem.